The purpose of this project is to investigate the use of a peripheral nerve allograft to provide a neurilemmal system (i.e., Schwann cells and their basement membranes) which might promote the regeneration of host nerve fibers at sites of injury to the peripheral or central nervous system. Initial studies are being performed to determine whether an immune response occurs to a nerve allograft and what influence tissue histocompatibility has on allograft survival. The results in rats show that a nerve allograft is antigenic and that grafts differing with respect to major histocompatibility antigens are rejected whereas grafts with minor antigens survive at the five weeks period the grafts were studied. Other results demonstrated that allografts (ganglia were used) with major or only minor histocompatibility antigens are rejected in the spinal cord. This demonstrates that immune mechanisms are operative in the spinal cord and that the central nervous system is not a privileged transplantation site. BIBLIOGRAPHIC REFERENCES: Zalewski, A. A. and Silvers, W. K.: A differential survival of ganglia and skin allografts in adult rats neonatally treated with bone marrow cells. Transplantation 23: 106-109, 1977. Zalewski, A. A. and Silvers, W. K.: The long-term fate of neurons in allografts of ganglia in Ag-B-compatible normal and immunologically tolerant rats. J. Neurobiol. 8: 207-215, 1977.